Deputy Attorney General Rod Rosenstein on Tuesday left open the possibility that he could fire special counsel Robert Mueller – though he said he would only do so for “good cause” and he had not seen any yet.

The issue came up in large part because Christopher Ruddy, the chief executive of Newsmax Media and a friend of Donald Trump, had raised the possibility on Monday that Trump might fire Mueller, who was recently appointed to lead the investigation into whether the Trump campaign coordinated with Russia to influence the 2016 presidential election.

“I think he’s considering perhaps terminating the special counsel,” Christopher Ruddy said during an appearance on PBS’s “NewsHour.” “I think he’s weighing that option.” He also told PBS he thought doing so would be “a very significant mistake.”

Trump technically has the authority to remove Mueller – either by ordering Rosenstein to fire him or ordering the regulations that govern his appointment repealed and then firing Mueller himself. Rosenstein noted that the chain of command would have to run through him and said he was confident Mueller would have “sufficient independence.”

Later, Sen. Susan Collins (R-Maine) asked Rosenstein point blank: “If President Trump ordered you to fire the special counsel, what would you do?”

“I’m not going to follow any orders unless I believe those are lawful and appropriate orders,” Rosenstein said. He noted he would need “good cause” to fire the special counsel, and added, “I am required to put that cause in writing. If there were good cause I would consider it. If there were not good cause, it wouldn’t matter to me what anybody says.”

Earlier, Rosenstein had said he did not see cause to fire Mueller.

Ruddy had been at the White House the same day as he made his assertion, though White House press secretary Sean Spicer said he did not meet with the president. Ruddy seemed to derive his assessment at least in part from comments Jay Sekulow, a member of Trump’s legal team, made over the weekend on ABC News’ “This Week.

Sekulow had said he was “not going to speculate” on whether Trump might remove Mueller but added he “can’t imagine the issue is going to arise.”

Spicer did not outright discount the notion of removing the special counsel, but he noted Ruddy was not a spokesman for Trump.

Attorney General Jeff Sessions, a former senator from Alabama, will face his former colleagues this afternoon in a hearing before the Senate Intelligence Committee. He is expected to face questions on contacts with Sergey Kislyak, the Russian ambassador to the United States, and his role in the firing of James B. Comey as FBI director.